Puzzled researchers are working hard to find out why.
An international team has examined the semen samples of nearly 43,000 men, collected from 1973 to 2011, and the results show a significant decline in Western men’s ability to produce sperm. Their research found men from North America, Europe, Australia and New Zealand have experienced a 52.4 percent drop in sperm concentration and a 59.3 percent drop in their sperm counts.
Western men made up about 75 percent of the study. The remaining 25 percent came from less developed regions in Africa, the Middle East, Asia and areas of South America.
New York Times spoke with Dr. Shanna H. Swan, one of the study’s authors and a professor at the Icahn School of Medicine at Mount Sinai in New York, who claimed that the analysis shows “this decline is strong and continuing.”
Dr. Swan went on to explain that the downtrend in Western countries means that we may find the cause in commercial chemicals. This includes everything from a mother smoking during pregnancy to exposure to phthalates.
Phthalates are a group of chemicals used to make plastics more flexible and harder to break. Phthalates have been found to disrupt the operation of male hormones and have been linked to birth defects. While the ability to detect these plasticizers has only been around since 2000, we know that less developed countries would not have been exposed to them as long as the West has, which could account for the difference in sperm production.
This is all still a theory. There has not been enough research done with phthalates to reach a definitive conclusion. It should also be mentioned that while an over-50 percent decrease in sperm production sounds high, it is a change from roughly 99 million sperm per milliliter to about 47 million. A significant enough drop to cause concern, but the human race is in no danger of ceasing reproduction any time soon.